JP4434294B2 - Liquid ejector - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus. In particular, the present invention relates to a liquid ejecting apparatus that can accurately detect the rear end of a recording object.

  An ink jet recording apparatus, which is an example of a liquid ejecting apparatus, performs recording on a recording material such as recording paper by ejecting ink from nozzle rows of a recording head. 2. Description of the Related Art In recent years, there is an ink jet recording apparatus that records on the entire surface of a recording material by performing recording up to the edge of the recording material (see, for example, Patent Document 1).

JP 2002-264319 A

  In order to perform recording up to the edge of the recording material, it is necessary to accurately detect the trailing edge of the recording material. One method of detecting the trailing edge of the recording object is to provide a photosensor next to the nozzle row of the recording head, and let this optical sensor detect the reflected light from the recording object, and the intensity of the reflected light is below the threshold value. There is a method of determining that there is a trailing edge in the part. However, in this case, if dark color recording is performed in the vicinity of the rear end of the recording object, the reflected light from the vicinity of the rear end becomes weak, so the rear end of the recording object may be erroneously recognized closer to the front than the actual one. is there. For this reason, there are cases where recording cannot be performed with high accuracy at the rear end of the recording object.

According to a first aspect of the present invention, there is provided a liquid ejecting apparatus that performs recording by ejecting a liquid onto a recording material in a liquid ejecting area, and scans the liquid ejecting area in a main scanning direction. A liquid ejecting head having a plurality of nozzles for ejecting the liquid onto the recorded material, a transport unit for transporting the recorded material in a sub- scanning direction orthogonal to the main scanning direction, and upstream in the sub-scanning direction from the liquid ejecting region. A main detection unit that detects a rear end portion of the recording material conveyed by the conveyance unit; and a reflected light from the recording material that is provided at a position overlapping the plurality of nozzles in the main scanning direction. detects, based on the intensity of the reflected light, it includes a sub-detection unit for detecting the rear end of the recording material in said liquid ejection area, and a control unit for controlling said plurality of nozzles, the control parts, the main detecting unit is the recording material Detecting a trailing end, when said conveying unit has a distance conveyance predetermined said recording material, the liquid from a nozzle provided in a position overlapping the said main scanning direction and the position of the sub-detection unit is provided The liquid ejecting apparatus is characterized in that the liquid is ejected from a nozzle that is downstream in the sub-scanning direction from the position where the sub-detecting unit is provided . According to the liquid ejecting apparatus, the sub-detecting unit can scan the recording material before recording is performed. Therefore, the sub-detecting unit can detect the recording object with high accuracy.

In addition, when the recording unit performs recording at the rear end, if the brightness of the recording data to be recorded in the vicinity of the rear end is higher than a predetermined value, the nozzle and the sub detection that overlap with the sub detection unit If the brightness of the recording data to be recorded near the rear end is lower than a predetermined value, the liquid is ejected from the nozzle overlapping with the sub-detecting unit. Recording may be performed by ejecting liquid from a nozzle downstream from the sub-detecting unit without ejecting the liquid. When the brightness of the recording data is high, the sub-detecting unit can accurately detect the rear end even if the sub-detecting unit scans the recording material after recording. For this reason, when the brightness of the recording data is high, the liquid can be ejected from some of the plurality of nozzles, and the recording throughput can be increased.
When the liquid ejecting apparatus is an ink jet recording apparatus, the control unit may determine the brightness of the recording data based on the recording density of the black ink to be ejected according to the recording data. In this case, the brightness of the recorded data can be easily determined.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 is a perspective view of an ink jet recording apparatus 10 which is an example of a liquid ejecting apparatus, and FIG. 2 shows a structure of a conveyance path of a recording object 11 in the ink jet recording apparatus 10. The ink jet recording apparatus 10 includes a mounting tray 12 on which a plurality of recording objects 11 are placed, a feeding roller 22 and a retard roller 24 that feed the recording objects 11 placed on the placing tray 12, and feeding. The recording material 11 fed by the roller 22 and the retard roller 24 is transported in the sub-scanning direction toward the ink ejection area, and the transport roller 32 and the transport driven roller 34, and ink is ejected onto the recording material 11 in the ink ejection area. A recording head 44 that performs recording, a discharge roller 52 and a discharge driven roller 54 that discharge the recording medium 11 from the ink ejection area, and a control unit 80 that controls the entire inkjet recording apparatus 10 are provided. The recording head 44 is placed on the carriage 42 and has a nozzle row composed of a plurality of nozzles on the lower surface.

  The control unit 80 ejects ink from the nozzle row of the recording head 44 while reciprocating the carriage 42 in the main scanning direction, which is a direction orthogonal to the sub-scanning direction. The control unit 80 scans the carriage 42 while transporting the recording material 11, and performs recording on the entire surface of the recording material 11. The ink jet recording apparatus 10 performs recording on both the forward path and the return path of the recording head 44.

  In addition, the ink jet recording apparatus 10 includes a main detection unit 200 that detects the recording material 11 between the feeding roller 22 and the conveyance roller 32, and a sub-detection unit 450 that detects the recording material 11 in the ink ejection region. As shown in FIG. 2, the main detection unit 200 includes a contact lever 210 that rotates by contacting and pressing the recording material 11 being conveyed between the feeding roller 22 and the conveyance roller 32, and the contact lever 210. It has a sensor 220 for detecting the rotation. The sub-detecting unit 450 is provided on the lower surface of the recording head 44 and determines the presence or absence of the recording object 11 by detecting the reflected light from the recording object 11. The sub-detecting unit 450 captures the reflected light from the recording object 11 with a width and detects the intensity. When the intensity is equal to or greater than a predetermined threshold value, it is determined that the recording object 11 exists below the recording head 44. When the intensity is less than the threshold value, the recording object 11 does not exist below the recording head 44. to decide. If the threshold is not more than the threshold value during scanning in the main scanning direction, it is determined that the end of the recording material 11 in the main scanning direction exists at this position.

  The ink jet recording apparatus 10 also includes a support rib 100 that supports the recording material 11 from below, a black ink absorbing material 110 that absorbs ink that has not adhered to the recording material 11, and an ink ejection region in the ink ejection region. Is provided with a guide frame 120 for guiding the recording object 11.

  In such a configuration, after the main detection unit 200 detects the trailing end of the recording material 11, the control unit 80 conveys the recording material 11 by a predetermined distance by the conveyance roller 32 and the conveyance driven roller 34. In this case, recording is performed on the rear end of the recording material 11 by ejecting ink from only the nozzles upstream of the support rib 100 in the nozzle array of the recording head 44. For example, the control unit 80 uses a distance equal to the distance between the position at which the contact lever 210 of the main detection unit 200 is in contact with the recording material 11 and the upstream end of the ink ejection area.

  FIG. 3 is a diagram for explaining the operation when the sub-detecting unit 450 detects the recording material 11. As the unrecorded recording material 11 is transported as shown in FIG. 3A, the sub detection unit 450 gradually overlaps the recording material 11, so that the detection value of the sub detection unit 450 is the minimum. Gradually higher from the value. When all of the sub-detecting unit 450 overlaps the recording material 11, the detection value of the sub-detecting unit 450 becomes constant at the maximum value. Further, when the recording material 11 is conveyed, the sub detection unit 450 gradually moves away from the recording material 11, and thus the detection value of the sub detection unit 450 gradually decreases. If all of the sub-detecting unit 450 is removed from the recording material 11, the detection value of the sub-detecting unit 450 becomes constant at the minimum value. The control unit 80 sets a threshold for edge detection to, for example, K1 that is an intermediate value between the maximum value and the minimum value.

  On the other hand, when black recording is performed in an area including the vicinity of the rear end (FIG. 3B), the intensity of the reflected light is the case where scanning is performed on the unrecorded recording material 11 in the vicinity of the rear end (FIG. 3). Weaker than 3 (a)). For this reason, the sub-detecting unit 450 detects the rear end inside the actual position. When the ink used for recording is a pigment ink, this tendency becomes remarkable because reflected light tends to be weak.

  Therefore, when the sub detection unit 450 scans the carriage 42 in the direction preceding the nozzle row of the recording head 44, the control unit 80 ejects ink only from the nozzles downstream from the sub detection unit 450 in the sub scanning direction. For this reason, the sub-detecting unit 450 can scan the recording material 11 before the recording head 44 performs recording. Therefore, even when black recording is performed by jetting black pigment ink near the rear end of the recording object 11, the sub-detecting unit 450 detects reflected light from the recording object 11 before recording. Therefore, the rear end of the recording object 11 can be detected with high accuracy.

FIG. 4 shows the relative positions of the sub-detecting unit 450, the nozzle row 440 of the recording head 44, the support rib 100, the ink absorbing material 110, and the guide frame 120. The ink absorbing material 110 is provided throughout the ink ejection area. The support rib 100 penetrates the ink absorbing material 110 from the bottom to the recording head 44. Each of the support ribs 100 includes a plurality of upstream ribs 102 and downstream ribs 104. The plurality of upstream ribs 102 are disposed at positions overlapping each other in the main scanning direction, and are provided upstream of the downstream ribs 104. The plurality of downstream ribs 104 are disposed at positions overlapping each other in the main scanning direction, and are disposed at positions overlapping each of the plurality of upstream ribs 102 in the sub scanning direction. The recording material 11 is conveyed in a state of being moved to one side (for example, the right side in FIG. 4) in the width direction. Therefore, the position of the other end of the recording medium 11 in the main scanning direction changes when the width of the recording medium 11 changes. Here, each of the plurality of upstream ribs 102 and the plurality of downstream ribs 104 is slightly smaller than the position where the other end passes when a sheet (L, postcard, A4, etc.) having a size according to the standard is conveyed. Located inside the paper. A portion of the guide frame 120 that overlaps the end of a sheet having a size according to the standard is notched, and the ink absorbing material 110 is exposed.
The nozzle row 440 of the recording head 44 overlaps the guide frame 120 at the upstream end. The sub detector 450 is arranged immediately downstream of the guide frame 120 so as not to overlap the guide frame 120.

  4 and FIG. 5 show which nozzles in the nozzle array 440 eject ink when recording is performed on the rear end of the recording material 11. When a dark color image is recorded in the vicinity of the rear end of the recording object 11, since the reflected light from the recording object 11 is weak in the vicinity of the rear end, the recording object 11 is scanned after recording. In this case, the sub-detecting unit 450 may erroneously determine that the rear end is inside the recording material 11 from the actual end. On the other hand, the control unit 80 of the present embodiment can detect the rear end with high accuracy by operating as follows.

  That is, when the recording head 44 is scanning in the direction in which the sub detection unit 450 precedes the nozzle row 440 (from right to left in FIG. 4), the control unit 80 starts from the upstream end of the nozzle row 440. Ink is ejected only from the rear end recording nozzle row 442 between the upstream ribs 102. Here, the sub-detecting unit 450 overlaps the rear end recording nozzle row 442 in the sub-scanning direction, but precedes the rear end recording nozzle row 442, and therefore scans the recording material 11 before recording is performed. Can do.

  Further, when the recording head 44 is scanning in the direction in which the nozzle row 440 precedes the sub detection unit 450 (from left to right in FIG. 5), the control unit 80 includes the sub detection unit in the rear end recording nozzle row 442. Ink is ejected only from the downstream nozzle row 442 b that does not overlap 450, and ink is not ejected from the upstream nozzle row 442 a that overlaps the sub-detecting unit 450. For this reason, even when the sub-detecting unit 450 precedes the nozzle row 440, it can scan the recording object 11 before recording.

FIG. 6 is a flowchart showing an operation when the ink jet recording apparatus 10 performs recording on the recording material 11. In the present embodiment, the recording range when recording data to be recorded on the recording material 11 is larger than the recording material 11 in the sub-scanning direction.
When the recording material 11 is transported to the ink ejecting area, the control unit 80 causes the recording head 44 and the sub-detecting unit 450 to scan in the main scanning direction, and ejects ink from the nozzle row 440 according to the recording data to perform recording. Perform (S20). At this time, the sub-detecting unit 450 is caused to detect the end of the recording material in the main scanning direction (S30). Then, the control unit 80 causes the transport roller 32 and the transport driven roller 34 to transport the recording material 11 (S40).

  When recording on the recording material 11 proceeds and the recording material 11 is conveyed, the main detection unit 200 detects the rear end of the recording material 11. After the main detection unit 200 detects the rear end of the recording object 11, the recording object 11 is set to a predetermined distance, for example, the position where the contact lever 210 of the main detection unit 200 contacts the recording object 11, and the ink ejection. When the sheet is conveyed by a distance equal to the distance from the end of the area on the conveying roller 32 side (S50: Yes), the control unit 80 of the ink jet recording apparatus 10 uses the rear end recording nozzle row 442 to Recording is performed at the rear end (S60).

FIG. 7 is a flowchart showing details of S60 of FIG. When the recording head 44 scans in a direction in which the nozzle row 440 precedes the sub-detecting unit 450 (S100: Yes), and the brightness of the recording data to be recorded near the rear end is less than the reference value (S105: Yes), control is performed. The unit 80 scans the recording head 44 and ejects ink only from the nozzles downstream of the sub-detecting unit 450, that is, the downstream nozzle row 442b, and does not eject ink from the upstream nozzle row 442a (S110). At this time, the sub-detecting unit 450 detects the intensity of the reflected light from the recording material 11. In S105, the control unit 80 determines the brightness of the recording data based on the recording density of the black ink to be ejected according to the recording data, for example.
When the recording head 44 scans in the direction in which the sub-detecting unit 450 precedes the nozzle row 440 (S100: No), the control unit 80 scans the recording head 44 while downstream of the guide frame 120 in the nozzle row 440. Ink is ejected from all the nozzles at the rear end recording nozzle row 442 (S120). Further, the control unit 80 scans the recording head 44 in a direction in which the nozzle row 440 precedes the sub-detecting unit 450 (S100: Yes), but the brightness of the recording data to be recorded near the rear end is equal to or higher than the reference value (S105). : Yes), ink is ejected from all of the trailing end recording nozzle rows 442 (S120).

  For this reason, the sub-detecting unit 450 can always scan the recording material 11 before recording is performed when dark recording is performed in the vicinity of the rear end. Further, since the number of nozzles for ejecting liquid is reduced only when scanning in one direction, the recording speed can be increased. Further, since the ink is not ejected from the upstream nozzle row 442a only when the brightness of the recording data to be recorded in the vicinity of the rear end is equal to or less than the reference value, the amount of decrease in the recording throughput is small.

  When the intensity of the reflected light detected by the sub-detecting unit 450 while the carriage 42 moves from one end to the other end of the ink ejecting area in the main scanning direction is greater than or equal to the threshold value at some point (S130: Yes), The controller 80 determines that the recording on the trailing edge of the recording material 11 has not been completed, and after the recording material 11 has been transported (S140), continues the recording according to the recording data. When the intensity of the reflected light detected by the sub-detecting unit 450 is less than or equal to the threshold value in the entire range (S130: No), the control unit 80 determines that recording has been performed up to the rear end of the recording object 11, and recording is performed. finish.

FIG. 8 is a flowchart showing a modification of S60 of FIG. In the present modification, the recording object 11 is substantially rectangular. The area to be recorded indicated by the recording data to be recorded on the recording medium 11 is larger than the width of the recording medium 11 in the sub-scanning direction.
When the recording material 11 is tilted (S200: Yes), the control unit 80 calculates the tilt (S210). For example, the control unit 80 determines whether or not the recording object 11 has an inclination by using the edge position detected when the top of the recording object 11 is first scanned and the edge position detected this time. To do. For example, the inclination of the rear end of the recording object 11 is calculated based on the conveyance amount of the recording object 11 in the main detection unit 200 and the deviation before and after the conveyance at the position where the intensity of the reflected light is smaller than the threshold value.

Then, the control unit 80 sets so as to gradually change the upper end of the nozzle row that ejects ink while scanning the recording head 44 in accordance with the inclination of the rear end of the recording material 11 (S220). Specifically, the rear end of the recording material 11 and the upper end of the nozzle row for ejecting ink are substantially overlapped. That is, when the recording head 44 scans and the rear end of the recording object 11 is shifted upstream, the control unit 80 gradually increases the upper end of the nozzle row that ejects ink in the nozzle row 440 as the recording head 44 scans. Shift to the upstream. Conversely, when the recording head 44 scans and the rear end of the recording medium 11 is shifted downstream, the control unit 80 moves the upper end of the nozzle row that ejects ink out of the nozzle row 440 as the recording head 44 scans. Gradually move downstream.
For this reason, the amount of ink absorbed by the ink absorbing material 110 without adhering to the recording material 11 can be reduced. Therefore, the ink use efficiency can be increased.

  When the recording head 44 scans in the direction in which the nozzle row 440 precedes the sub detection unit 450 (S230: Yes), the control unit 80 ejects ink from only the downstream nozzle row 442b while scanning the recording head 44. (S240). When the recording head 44 scans in the direction in which the sub-detection unit 450 precedes the nozzle row 440 (S230: No), the control unit 80 ejects ink from all the rear end recording nozzle rows 442 while scanning the recording head 44. (S250). After scanning, the controller 80 conveys the recording material 11 (S260).

  If the intensity of the reflected light detected by the sub-detecting unit 450 is less than or equal to the threshold value in the entire range (S270: No), the control unit 80 determines that recording has been performed up to the rear end of the recording object 11, and recording is performed. Exit.

  The ink jet recording apparatus 10 is an example of a liquid ejecting apparatus, and the carriage 42 is an example of a liquid ejecting head. However, the liquid ejecting apparatus is not limited to this. Another example of the liquid ejecting apparatus is a color filter manufacturing apparatus that manufactures a color filter for a liquid crystal display. Still another example of the liquid ejecting apparatus is an electrode forming apparatus that forms electrodes such as an organic EL display and an FED (surface emitting display). Still another example of the liquid ejecting apparatus is a biochip manufacturing apparatus that manufactures a biochip. The liquid ejecting apparatus of the present invention includes other liquid ejecting apparatuses having industrial use. The recording object is an object on which recording is performed by ejecting a liquid. In addition to recording paper, a circuit board on which circuit patterns such as electrodes of a display are recorded, a CD-ROM on which a label is printed, DNA The preparation on which the circuit is recorded is included.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

FIG. 2 is a perspective view showing the ink jet recording apparatus 10 with a cover removed. FIG. 3 is a diagram illustrating a structure of a conveyance path of a recording object 11 of the ink jet recording apparatus 10. FIG. 6 is a diagram for explaining an operation when the sub-detecting unit 450 detects the recording object 11. FIG. 3 is a diagram illustrating nozzles that eject ink when recording is performed on the rear end of the recording material. FIG. 3 is a diagram illustrating nozzles that eject ink when recording is performed on the rear end of the recording material. 6 is a flowchart showing an operation when recording is performed on the rear end of the recording object 11; The flowchart which shows the detail of S60 of FIG. The flowchart which shows the modification of S60 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 11 ... Recording object, 12 ... Loading tray, 22 ... Feeding roller, 24 ... Retard roller, 32 ... Conveyance roller, 34 ... Conveyance driven roller, 42 ... Carriage, 44 ... Recording head, 48 ... guide shaft, 52 ... discharge roller, 54 ... discharge driven roller, 80 ... control unit, 100 ... support rib, 102 ... upstream rib, 104 ... downstream rib, 110 ... ink absorber, 120 ... guide frame, 200 ... main Detection unit, 210 ... contact lever, 220 ... sensor, 440 ... nozzle row, 442 ... rear end recording nozzle row, 442a ... upstream nozzle row, 442b ... downstream nozzle row, 450 ... sub-detection unit

Claims (3)

A liquid ejecting apparatus that performs recording by ejecting liquid onto a recording material in a liquid ejecting area,
A liquid ejecting head having a plurality of nozzles that scan the liquid ejecting area in a main scanning direction and eject the liquid onto the recording material;
A transport unit for transporting the recording material in a sub- scanning direction perpendicular to the main scanning direction;
A main detection unit that is provided upstream of the liquid ejection region in the sub-scanning direction and detects a rear end portion of the recording material conveyed by the conveyance unit;
Provided at a position overlapping the plurality of nozzles in the main scanning direction, detects reflected light from the recording material, and based on the intensity of the reflected light, a rear end portion of the recording material in the liquid ejecting area A sub-detection unit for detecting
A control unit for controlling the plurality of nozzles ;
With
Wherein the control unit, the main detecting unit detects the rear end of the recording material, when the transport unit is transported distance predetermined for the recording material, and a position where the sub-detection unit is provided The liquid is not ejected from the nozzle provided at the overlapping position in the main scanning direction, and the liquid is ejected from the nozzle downstream in the sub scanning direction from the position at which the sub detection unit is provided .
A liquid ejecting apparatus. When the controller further performs recording on the rear end,
When the brightness of the recording data to be recorded in the vicinity of the rear end portion is higher than a predetermined value, the liquid is ejected from a nozzle that overlaps with the sub detection unit and a nozzle that is downstream from the sub detection unit. Make a record,
When the brightness of the recording data to be recorded in the vicinity of the rear end portion is lower than the predetermined value, the liquid is not ejected from the nozzle overlapping with the sub-detection unit, and downstream from the sub-detection unit. The liquid ejecting apparatus according to claim 1, wherein recording is performed by ejecting the liquid from a certain nozzle. The liquid ejecting apparatus is an ink jet recording apparatus,
The liquid ejecting apparatus according to claim 2 , wherein the control unit determines the brightness of the recording data based on a recording density of black ink to be ejected according to the recording data.

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